Firing mechanism for automatic firearms



Sept. 21, 1937. M. A. BROWNING FIRING MECHANISM FOR AUTO MATIC FIREARMS 19, 1934 Original Filed Feb.

patented Sept. 21, 1937 Ul ilTED if.

TENT OFFICE FIRING MECHANISM FOR AUTOMATIC FIREARMS Original application February 19, 1934, Serial Divided and this application March 19, 1935, Serial No. 11,794

6 Claims.

The object of the invention is to provide a firearm of the type shown in the Browning Patent No. 1,293,022 with a firing mechanism including a firing pin which is automatically cocked and released by movement of a gas operated actuating means. v

This present application constitutes a division of my copending application for Automatic firearm, Serial No. 711,846, filed February 19, 1934.

In the accompanying drawing I have shown the embodiment of the invention which I now deem preferable, but it will be understood that the drawing is intended for illustrative purposes only and is not to be relied upon as limiting or defining the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawing:

Fig. l is a side view of a firearm embodying the invention.

Fig. 2 is an enlarged fragmentary View of the rear portion of the firearm, this view being partly a side view and partly a longitudinal sectional view.

Fig. 3 is a view similar to Fig. 2, but showing the parts in different relative positions.

Fig. l is a tran verse sectional view taken along the line L 3 of Fig. 2.

Referring to the drawing, l represents as an entirety the main breech casing which is generally rectangular in section, as shown in Fig. 4. As shown, the casing is formed from a single piece of steel although I do not necessarily limit myself to this integral construction. The portion l of the casing is formed to receive the rear end of a barrel 2. Behind the portion I are two main side walls l l connected near the center by an integral top plate E. An opening I is provided at the front of the top plate l, which opening is normally closed by a pivoted cover 3 held by a releasable latch 3 The bottom of the casing is normally closed by separate plates 5 and 6. The rear of the casing is normally closed by a plate l flanged at its sides and having ribs (not shown) adapted to enter grooves formed in the side walls l l A suitable latch l serves to normally hold the end plate 3 in place; Carried by the plate 1 at opposite sides thereof are two brackets 8, 8 carrying handles 9, 9.

The casing l is provided with an integral extension l which extends forward underneath the barrel. This extension is hollow and it serves to engage and retain a piston tube l6. At its forward end the tube i6 is connected with, and supported by, the barrel. Longitudinally movable along the bottom of the main casing is an operating slide 21, this slide being connected with a piston 28 and a piston rod 29 positioned within the piston tube 55. A cylinder 3| is provided in the forward end of the tube l6, and the piston accurately fits the said cylinder. A gas passage extends from the bore of the barrel to the cylinder, to enable the gases of explosion to enter the cylinder and act upon the piston to force it rearward.

. For returning the slide in the forward direction after having been moved rearward by the piston and piston rod, there is provided an action spring 32 supported upon and guided by a rod 33. Preferably the spring 32 and rod 33 extend into a hollow bufier 34 carried by the rear plate I. The spring at its rear end abuts against a head 35 detachably secured in place in the bufier. The spring at its forward end extends into an aperture in the slide 21 and abuts against a shoulder 36. A hole 36 provides clearance for the rod 33 when the slide is in its rear position. The slide 21 serves to operate the feeding, loading and firing mechanisms of the gun.

Extending transversely through the casing below the rear portion of the barrel is a cartridge feed channel 31 adapted for the reception of a cartridge belt such as A. Transversely movable below the feed channel 37 is a feed slide 39, which is actuated by means of the operating slide 21. As shown, the main portion of the feed slide is above the operating slide, and in this case the operating slide has a cam groove in its upper face into which projects a pin carried by the feed slide. The shape of the groove is such that the feed slide is reciprocated transversely as the operating slide reciprocates longitudinally. The feed slide carries a pawl which engages the cartridge belt to bring a new cartridge into a position below the barrel at each actuation of the operating slide.

Preferably the operating slide 27 and the parts associated therewith are removable from the firearm at the rear thereof. To efiect such removal it is necessary first to remove the spring 32 and the rod 33 and to then remove the end plate 1 with the parts carried thereby. The slide is then substantially free to be withdrawn in the rearward direction, except for the fact that the pin on the feed slide must be disengaged from the groove in the operating slide.

The firearm is provided with a reciprocating breech bolt 55 which is guided between the side walls I l of the casing. The breech bolt is operated and controlled by mechanism operated by the slide '21, this mechanism being similar to that disclosed in Patent No. 1,293,022 to John M. Browning. As shown in Fig. 3, the breech bolt 45 is connected with the slide 27 by means of two links it and t! pivotally connected with each other at 58. The link G6 is pivotally connected with the breech bolt at 49 and the link M is pivotally connected with the slide at 5B. When the slide 2? is in its rear position, as shown in Fig. 2, the two links All and at are substantially in alignment and an extension 46 on the link 46 engages the top wall l of the casing to hold the links in the relative positions shown.

When the slide 2'5 moves forward under the influence of the action spring 32 the two links at and 41 and the breech bolt 45 move in unison with it until the breech bolt nearly reaches its forward position, the link d6 being then approximately in register with the opening i in the top wall of the casing. At or about the time that the link comes into register with the opening the curved portion de of the link it engages two cams projecting inward from the respective side walls l i of the casing. In the drawing only the cam on the left hand side is clearly shown, but it will be understood that there is a similar cam on the right hand side. These cams 5i cooperate with the curved portion lt of the link 46 to force the link upward into the opening i the rear end portion of the link abutting against the rear wall of the opening, as clearly shown in Fig. 3. In the meantime the slide 27 has continued its forward movement, thus bringing the link 41 into a substantially upright position. With the parts in the position shown and described, the breech bolt is firmly locked in its forward or breeched position and is well adapted to resist the recoil action incident to firing. Following firing the slide 27 is moved rearward by the action of the gases of explosion in the manner already described, the link 4i serving first to draw the link at downward out of locking position and then to move the link 46 and also the bolt 55 rearward to the positions shown in Fig. 2.

Reference has already been made to the fact that the slide 2'?! can be removed through the rear of the casing. It will be understood that the breech bolt :5 and the links 46 and 41 are similarly removable, all of these parts being removable as a unit.

A firearm incorporating the present invention is intended to be used with cartridges having annular grooves in the heads thereof, and the front end of the breech bolt is provided with vertical ribs 52, 53 which cooperate to form a vertical groove for receiving and retaining the heads of the cartridges. When the breech bolt is in its forward position, as shown in Fig. 3, the head of the cartridge which is in central position in the feed channel 3i is vertically below the groove in the front of the breech bolt. For withdrawing the cartridge from the feed channel and lifting it into proper relationship to the breech bolt there is provided an extractor 54. This extractor is provided with a pivot pin 55 which fits a transverse pivot opening in the breech bolt, the extractor thus moving bodily rearward and forward as the breech bolt moves. The extractor 54 is provided with a transversely extending tooth 56 which is so shaped and positioned as to enter the groove in the cartridge when the breech bolt and the extractor are in their forward positions, as shown in Fig. 3.

A suitable cam mechanism is provided for controlling and guiding the relative movements of the extractor, but as this cam mechanism constitutes no part of the present invention and is fully disclosed in my said application No. 711,846, it is not necessary to include a detailed description of it in this present specification. It is sufficient to say that when the breech bolt moves rearward the extractor moves rearward and upward, causing the cartridge to be extracted and then lifted into alignment with the chamber in the barrel. As the I breech bolt returns in the forward direction, the cartridge is inserted into the chamber and the extractor is again moved downward into position to engage another cartridge in the feed channel. An ejector (not shown) serves after firing to eject the empty shell from the ejection opening '16 in the right wall of the casing.

Mounted in the breech bolt is a firing pin 80 biased in the forward direction by means of a spring 8!. Pivoted on the breech bolt is a sear 82 adapted to engage a shoulder 83 on the pin, as shown in Fig. 2. A spring pressed plunger 84 serves to bias the sear toward its operative position. The firing pin Oil is provided with a shoulder 85 which is adapted to be engaged by a shoulder 86 on the slide 27. From the description which has already been presented, it will be understood that the slide 2 moves rearward to a greater extent than does the breech bolt 49 and it will, therefore, be evident that in moving from the position shown in Fig. 3 to the position shown in Fig. 2 the shoulder 86 will engage the shoulder 35 to move the firing pin 8:! relatively rearward into its cocked position so that it can be engaged and held by the sear 82. As the parts move forward from the position shown in Fig. 2 to the position shown in Fig, 3 the lower tail portion of the sear 82 is engaged by means projecting transversely of the slide 2'! and having a shoulder 81! thereon, the sear being thus withdrawn from the firing pin and the firing pin being thus released to move forward under the influence of the spring 8| and to eifect firing of the cartridge.

For holding the slide 21 in its rear position, as shown in Fig. 2, there is provided a second sear 88 pivoted to the bottom plate 5. This sear is spring pressed upward and engages a notch 89 in the bottom of the slide. Carried by the rear plate 7 is a manually operable trigger 98 having a tail portion 9! which projects forward through an opening in the plate and is adapted to engage the sear 88. A spring pressed plunger 92 tends to hold the trigger in its rearward inoperative position.

By referring to Fig. 2, it will be observed that when the slide 2'1 is held by the sear 88 the shoulder 85 on the firing pin is directly engaged by the shoulder 86 on the slide, the firing pin thus being firmly held entirely independently of the sear 32. This makes it impossible for the firing pin to be accidentally released by vibration or otherwise while the breech bolt is in its rear position.

In initially loading the gun in order to start firing it is ordinarily necessary to operate the mechanism of the gun by hand in order to withdraw the first cartridge from the belt and transfer it into the position shown in Fig. 2. For this purpose there is provided a handle 93 extending through a slot 9G in the left side wall of the casing and fitting a hole 95 in the slide 21. The slot 94 is enlarged at its rear end and the handle 93 is so formed that it can be removed only when in register with the enlarged rear end of the slot.

From the foregoing description the operation of the gun will be readily understood and only a very brief summary is needed. When the trigger 90 is pressed forward the sear 88 is disengaged from the slide 21 and the slide moves forward, causing the several parts to assume the positions shown in Fig. 3. When these positions are reached the sear 82 is engaged by the shoulder 87 and is moved, thus releasing the firing pin 8|] and causing firing. Thereupon the gases of explosion enter the cylinder 3| and drive the piston 28 rearward, thus moving the slide 2'! rearward and causing the various parts of the gun to assume the relative positions shown in Fig. 2. During this rearward movement a new cartridge is extracted from the belt and the shell of the exploded cartridge is ejected in the manner already described. If, in the meantime, the trigger 90 has been released and permitted to resume its normal position, the slide is caught and held by the sear 88 and no further firing takes place. If, however, the trigger 90 is held in its forward firing position the parts immediately again move forward to the firing position shown in Fig. 3 and firing again occurs. Thus volley firing may be continued so long as the trigger 90 is held and so long as the supply of cartridges in the belt is not exhausted.

What I claim is:

1. An automatic firearm comprising in combination, a breech casing, a barrel, a longitudinally and rectilinearly movable breech bolt in the casing, a longitudinally movable operating slide ad- J'acent the bolt which upon firing automatically moves rearward to a greater extent than the bolt, two connected operating links pivotally connected respectively with the bolt and with the slide, the bolt connected link when the bolt and slide are in forward positions serving to lock the bolt and the slide connected link upon rearward movement of the slide serving to effect unlocking and then to move the other link and the bolt rearward, a firing pin on the bolt longitudinally movable relatively thereto and biased for forward movement, means on the slide engaging the firing pin during rearward movement and serving by reason of the greater movement of the slide to move the firing pin rearward relatively to the bolt, the last said means serving to positively hold the pin while the slide is in its rearward position, a sear on the bolt adapted to hold the firing pin in its rear or cooked position, and means automatically operable when the slide reaches its forward position for releasing the sear to thereby release the firing pin.

2. In an automatic firearm, the combination of a breech casing, a barrel, a breech bolt automatically and rectilinearly movable from and to a breeched position upon firing, operating means connected with the bolt to move simultaneously therewith, a firing pin on the bolt and movable relative thereto to and from a firing position and biased for movement to a firing position, means on the operating means for moving the firing pin to cocked position, a sear on the breech bolt adapted to engage and hold the firing pin in cocked position, and means on the operating means projecting transversely therefrom for automatically releasing the firing pin from engagement with the sear when the bolt has reached its breeched position.

3. An automatic firearm comprising in combination, a breech casing, a barrel, a longitudinally movable breech bolt in the casing, a longitudinally movable operating slide adjacent the bolt which upon firing automatically moves rearward, means connecting the slide with the bolt to enable the former to move the latter but to a lesser extent, a firing pin on the bolt longitudinally movable relatively thereto and biased for forward movement, means on the slide engaging the firing pin during rearward movement and serving by reason of the greater movement of the slide to move the firing pin rearward relatively to the bolt, the last said means serving to positively hold the pin while the slide is in its rearward position, a sear on the bolt adapted to hold the firing pin in its rear or cooked position, and means on the slide projecting transversely therefrom for engaging and releasing the sear to thereby automatically release the firing pin when the bolt and slide reach their forward positions.

4. An automatic firearm comprising in combination, a breech casing, a barrel, a longitudinally movable breech bolt in the casing, a longitudinally movable operating slide adjacent the bolt which upon firing automatically moves rearward to a greater extent than the bolt, two connected operating links pivotally connected respectively with the bolt and with the slide, the bolt connected link when the bolt and slide are in forward positions serving to lock the bolt and the slide connected link upon rearward movement of the slide serving to elfect unlocking and then to move the other link and the bolt rearward, a firing pin on the bolt longitudinally movable relatively thereto and biased for forward movement, means on the slide engaging the firing pin during rearward movement and serving by reason of the greater movement of the slide to move the firing pin rearward relatively to the bolt, the last said means serving to positively hold the pin while the slide is in its rearward position, a sear on the bolt adapted to hold the firing pin in its rear 01' cocked position, and means on the slide for engaging and releasing the sear to thereby release the firing pin when the bolt and slide reach their forward positions.

5. An automatic firearm comprising in combination, a breech casing, a barrel, a longitudinally movable breech bolt in the casing, a longitudinally movable operating slide adjacent the bolt which upon firing automatically moves rearward, means connecting the slide with the bolt to enable the former to move the latter but to a lesser extent, a firing pin on the bolt longitudinally movable relatively thereto and biased for forward movement, means on the slide engaging the firing pin during rearward movement and serving by reason of the greater movement of the slide to move the firing pin rearward relatively to the bolt, the last said means serving to positively hold the pin while the slide is in its rearward position, a sear on the bolt adapted to hold the firing pin in its rear or cocked position, a second manually operable sear on the casing adapted to hold the slide in its rear position, and means on the slide for engaging and releasing the first sear to thereby release the firing pin when the bolt and slide reach their forward positions after having been released by the second sear.

6. An automatic firearm comprising in combination, a breech casing, a barrel, a longitudinally movable breech bolt in the casing, a firing pin on the bolt longitudinally movable relatively thereto and biased for forward movement, a sear on the bolt adapted to hold the firing pin in its rear or cocked position, a longitudinally movable operating slide adjacent the bolt which upon fir ing automatically moves rearward, a i second manually operable sear 0n the casing adapted to hold the slide in its rear position, pivotally connected locking links, meansconnecting the slide with the bolt to enable the former to move the latter but to a lesser extent, means on the slide engaging the firing pin during rearward movement and serving by reason of the greater move- 10 ment of the slide to move the firing pin rearward relatively to the bolt, the last said means holde ing the firing pin entirely independently of the first searso longas the slideis held in its rear position by the second sear, and means on the slide for engaging and automatically releasing the first sear to thereby release the firing pin when the bolt and slide reach their forward positions after having been released by the second sear.

MARRINER A. BROWNING. 

